Digital audio converters (DACs) come in all sizes, shapes, and prices. You can find simple digital converters on Amazon for as little as $7 or state-of-the-art units that cost as much as a comfortable middle-class home. To say that today’s audiophiles have choices is an understatement. But what price point offers the highest value or greatest bang for the buck? For some audiophiles, one of the best options in the past was to buy the most expensive DAC they could afford and then use it until it became completely obsolete. This “buy and hold” strategy is exactly what I have employed with top-shelf analog gear—my 20-plus-year-old Pass X150.3 power amplifier still performs at a competitive level compared with new designs. But when it comes to DACs, advancements have been rapid and the list of “must-have” features has grown and changed. I know of no twenty-five-year-old consumer DACs that can deal with 192/24 high-resolution files, or DSD files, or that can offer Bluetooth connectivity capabilities. Sure, some still sound wonderful with 44.1/16 Red Book files, but digital technology has moved on.
When it comes to DACs I believe the best price/performance ratios are delivered by “affordable” ones such as the unit up for review, the iFi Audio xDSD. Indeed iFi was founded on the idea that high-performance digital products can be reasonably priced. Its most expensive, recently introduced “flagship,” the iFi Pro iDSD, is only $2499, but includes a “quad stack” of Burr-Brown DAC chips and a selectively engageable General Electric 5670 tube in the signal path! The iFi xDSD may not have quite that many DAC chips and has no tubes, but it does have a remarkably rich feature set and the ability to serve as both a desktop or portable unit. You could use the xDSD DAC with your computer, smartphone, CD transport, streamer, or even as a digital source-selector and decoder for a room-based stereo system. And, yes, it supports MQA. Its MSRP is a princely $399.
The xDSD is small and enclosed in an aluminum/magnesium chassis. The entire xDSD measures approximately 2¾” by 7/8″ by 3¾” and weighs 127 grams (0.28 lbs.). The DAC supports resolutions up to 768/24 PCM and DSD512 via its Burr-Brown DSD1793 DAC chip. The xDSD offers some user-selectable digital processing in the form of two PCM filters: “listen” and “measure.” As you might suspect, iFi recommends the “listen” setting over the “measure” setting, even though the “measure” setting offers slightly better specs.
The xDSD uses an analog rather than a digital volume control. With 101 discrete steps, iFi calls this newly designed output system the “Cyberdrive.” According to iFi, “the OV4627 ultra-low-noise FET input op-amp and W990VST digitally controlled stepped attenuator deliver a new level of sound quality.” The stepped volume control, 3D+ Matrix, and X-Bass can be completely bypassed when a user selects the line-output mode, which is recommended when using the xDSD connected to an analog preamplifier.
Unlike many portable DACs, which rely on a smartphone’s connection for power, the iFi xDSD has a built-in battery, so it won’t be running down your smartphone or portable source device’s power as rapidly when you’re listening. The internal lithium-polymer battery produces 2200mAh which, according to iFi, allows between six and eight hours of playing time (depending on the sample and bit rate of the music files and the efficiency of your attached earphones).
When you’re not jaunting about town, the xDSD can be powered via its micro USB charge port. The port can get power from virtually any standard USB 2.0 or 3.0 connection. You can connect it to one of your computer’s USB outputs or use a separate free-standing USB wall-wart. Also, iFi makes a USB power device called the iUSB 3.0 ($429), which can be placed between a computer’s USB output and the xDSD’s micro-USB power input as well as its primary USB source input.
The xDSD uses four, small, variably colored LEDs on its front panel to indicate its current operating states. If you are color-blind, this could be an issue. The centrally located volume control also uses a colored center section to indicate your volume level. White means a line-level output of two volts; no light signals a muted output; a blue light is -95 to -76dB down in level; a magenta color is -75 to -58dB down; cyan is -57 to -40dB down; green is -39 to -22dB down; yellow/green is -21 to -4dB down; and red indicates that you’re at -3 to +6dB, which tops out the xDSD’s potential output level. Along with these four LEDs the front panel has two LEDs on the right side. When the top button is lit, the iFi’s 3D+ circuit is engaged; when the bottom LED is lit, the X-Bass function is active. When both are lit, both are activated. Your selection is made via a small soft-rubber button on the extreme right side of the front panel that also serves as the Bluetooth “linking” button.
The xDSD supports multiple input options. Sources include USB, SPDIF coaxial, TosLink, and Bluetooth. The Bluetooth connection supports both aptX and ACC. The xDSD’s clocking system is derived from parent company AMR’s DP-777 DAC in conjunction with a memory buffer. This circuit reportedly reduces source jitter, which for Bluetooth, can be as high as several thousand picoseconds. The custom Bluetooth system includes the aptX codec that reportedly delivers “near CD-quality” sound from Android and Apple devices.
On the output side, the xDSD has one option—a mini-stereo output on its front panel. Given the DAC’s projected use and lack of front-panel real estate, the mini-stereo plug connection, rather than the studio-standard ¼” headphone jack, makes perfect sense. But if you have headphones that have only a ¼” stereo jack, you will need an adapter to reduce that ¼” stereo to a mini-stereo jack. The two adapters I had around were almost 2″-long metal columns that when combined with the stereo jack (such as the Furutech) made for a weighty 5″-long metal pole sticking out from the front of the xDSD. Even using the Grado adapter (which has a short flexible cable between its input and output connectors) made for a rather ungainly package.
Most audio devices that I know of are not left- or right-handed (unlike baseball gloves), but the xDSD is an exception. To see all the controls clearly you need to place the xDSD on the left side of your desktop. Why? Because that adapter combo I mentioned, and even a good percentage of mini-stereo-terminated cables, will obscure the control LEDs when the xDSD is on your right side. For easier usage, I installed two 2″ by 2″ squares of high-density foam, one under the xDSD and the other supporting the converter jack, beneath the xDSD to raise it off the desktop. This way I could use the xDSD when it was on my desktop’s right side (which is where the rest of my computer electronics are located). Also, elevating the xDSD slightly off the desktop makes it far easier to turn the volume knob.
Linking to a Bluetooth source was as simple as holding down the BT button while putting your smartphone into pairing mode via the settings menu. My iPhone SE linked with no issues, as did my HiDiz AP-60 II portable player. Since this was the same weekend as the Telluride Music Festival, which is broadcast live over KOTO, Telluride’s community radio station, I spent a good deal of time tethered to the iPhone/xDSD combo while working out and doing household errands.
The xDSD proved to be a remarkably agnostic headphone interface. It had enough juice to drive the HiFiMan HE1000 V2 headphones to satisfying levels, with 21dB of additional gain to spare. Conversely, with the sensitive 121dB/1mW Earsonics S-EM9 there was no background hiss whatsoever. I used a wide variety of earphones with the xDSD including AKG-7xx, Meze Classic 99, Sennheiser HD 700, Sony MDR-Z1R, MrSpeakers Ether, Astell&Kern Billie Jean, and Ultimate Ears Reference Remastered CIEMs. In every case the xDSD introduced no noticeable alterations in the intrinsic harmonic balance of the headphones attached to it.
One of the primary intended functions of the xDSD is portable use. Its shape and design add to its “pocketability.” The knurled volume knob is easy to locate blind while the xDSD is in your pocket. The other pushbutton on the front panel is set into the body of the DAC, so it can’t easily be activated accidentally. Pushing the volume button inwards puts the xDSD into mute mode—this was also easy to do while the unit was still in my pocket.
My optimum desktop-performance signal chain employed the HiFiMan HE1000 V2 headphones tethered to the xDSD. The xDSD was fed from the iFi iUSB 3.0 USB which was connected via USB 3.0 to a Mac Pro 2013 Titanium Trashcan running Roon. In portable mode, my favorite combination was the new Earsonics EM10 CIEM paired with the xDSD. I was impressed by how close the EM10’s came to recreating the HE1000 V2’s detailed and complex soundstage, as well as that puff-of-air bottom end that I heard through the xDSD/HiFiMan HE1000 V2 combo.
One nit I have to pick with the xDSD: If there is no active source, the xDSD produced a low-level whine/hum that continued, unabated, until it locked onto an active source. Also, occasionally I noticed when going from an MQA track to a FLAC or DSD track the tune would begin with the first ½ second clipped off.
When compared to the ergonomics of a pair of Bluetooth-enabled earphones or a headphone connected directly to your smartphone with phone controls in its cabling, the primary disadvantage of the xDSD is that you can’t go smoothly from listening to music on your smartphone to answering phone calls with a touch of a button, as you can with these other two connection schemes.
As I said, the xDSD is remarkably unbiased in terms of favoring a certain pair of earphones or championing a particular sonic coloration. During my multiple listening sessions with many different headphones and sources, the most sonically prominent feature I noticed was the recording’s shortcomings rather than any issues created by the xDSD/headphone combination. In other words, the weakest sonic link in the source/xDSD/headphones system was the recorded source 99% of the time.
Compared with my current reference headphone amplifier, the Sony TA-ZH1ES ($2399), the xDSD’s output sounded similar with most headphones, but not identical. The Sony produced more bass energy than the xDSD with some earphones, such as the Earsonics EM-10 CIEM. While on a purely subjective pleasure level there is something special about listening to music through the Dennis Had-designed Dragon Inspire IHA-1, the xDSD delivered fuller, yet tighter and more incisive bass when connected to the HiFiMan HE1000 V2 headphones than the Dragon Inspire, especially on tracks with thick bass lines such Years & Years’ “Palo Santo.”
Speaking of bass, one feature on the xDSD that I did not find terribly useful was the X-Bass function. With the vast majority of headphones switching in the X-Bass didn’t seem to do much, if anything, to change bass response. When I switched on iFi’s 3D+ circuitry it did seem to s-t-r-e-t-c-h the soundstage wider, but the effect was also accompanied by a loss of image specificity and centerfill.
Compared to the sound directly from the headphone output of my iPhone SE, with the highly efficient Earsonics EM-9 universal in-ears, which the iPhones’ internal headphone amp had no problem driving to well past my max volume limit, the xDSD yielded a less brittle upper midrange, wider soundstage, and better image specificity on the same tracks. This was especially noticeable on the Tidal version of the Demi Lovato single “Sorry.”
I see two quite different “types” of audiophile as the primary customers for the xDSD. First, younger, more mobile-oriented audiophiles with smartphones and portable computers could find the xDSD to be the perfect “step-up” audio device to improve sound from all sources. Long-time audiophiles (the ones with the 25-year-old DACs that they still love for Red Book) could add an xDSD to their system as an auxiliary digital device that would give them access to all the newest high-resolution files, streams, and digital codecs for a pittance of the price they paid for their “main-squeeze” DAC. Both types of audiophile will be pleased and impressed by the xDSD’s flexibility, utility, performance level, and overall value. I know I was.
Specs & Pricing
Type: Portable/desktop DAC/headphone amplifier
Inputs: USB, coaxial SPDIF, TosLink, Bluetooth
Formats supported: PCM up to 768/24; DSD to DSD512
Output: Unbalanced, fixed and/or variable
Dimensions: 66.5 x 19 x 95mm
Weight: 127g (0.28 lbs.)
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